The present invention relates to anti-friction bearings and assemblies therefor, and more particularly to bearings which operate under conditions characterized by extreme performance demands such as high radial loads and long lifetime requirements.
Anti-friction bearings are often used in a variety of applications in which the bearing assemblies experience high external loads during operation. Externally applied loads generate contact stress between the raceways and the loaded rolling elements. Excessive radial loads on bearings are detrimental to bearing life. In some applications, bearing assembly misalignment can develop under certain loading conditions. Unwanted operational noises can be experienced, particularly during these types of high loading conditions.
One such application during which high loads are developed is on agricultural equipment. Agricultural equipment must effectively process a high volume of agricultural product in short times during harvests under conditions characterized by a high concentration of particulate matter, such as dirt, dust, moisture and plant particles. Exemplary of agricultural equipment in this regard are hay balers. One type of hay baler, a round baler, has a baling chamber defined by a number of sidewalls and has a series of rotating endless belts which roll and compact hay and forage material together into a large, round bale. The rollers extend between the baler sidewalls and drive the endless belts. The rollers are typically chain or belt driven. Each roller may be mounted in the baling chamber with one or more bearings located at opposite ends of the roller. Some current hay balers utilize bearings with hex-shaped inner races which engage complementarily-shaped hexagonal shafts extending out from the ends of the rollers. These bearings have been known to exhibit a loud and annoying "pounding" or "knocking" noise during operation of hay balers. This pounding or knocking is believed to be caused by the constant loading and unloading of the baler rollers during the forming of hay bales within the baling chamber. As the density of the bale grows, it exerts forces on the sidewalls of the baler which can cause the bearings to become misaligned. It is believed that the knocking or pounding noise occurs when the bearings are misaligned.
In hay baler applications and particularly round hay baler applications, it is also desirable to allow a certain amount of axial movement between the shaft and inner race of the bearing assemblies to reduce or eliminate the axial or thrust loads borne by the bearing assembly and to allow for easier assembly. Accordingly, in attempting to solve problems such as undesirable noise development and in seeking ways to better handle high bearing loads, one must also allow for and take into account this axial movement when working on these types of devices.